The present invention generally relates to techniques for forming three-dimensional (3D) nanostructures by employing dry lubricant and high speed shock, and more particularly to methods for fabricating metal nanopatterns using laser induced shockwaves.
Metal forming has always played an important role within the manufacturing industry because of its multiple advantages, including low cost, low waste, smooth surface, high speed and high uniformity. However, nanoscale metal forming is very difficult because of the limited formability arising from size effects. Because of these difficulties, it would be desirable to design a more effective nanoscale metal forming technique.
Due to high mechanical strength, nonlinear optical response, high electrical and thermal conductivity, nanoscale metallic structures are of considerable interest to broad fields, including plasmonics and nanoelectromechanical systems (NEMS). Promising versatile applications are proposed, ranging from biosensors, photovoltaic devices to subwavelength optical devices. To realize the potential of these materials, there is a need to develop low cost and high-throughput techniques that can engineer complex nanostructures on metal surfaces. Although various approaches such as lithography and microcutting have been developed to generate nano metallic features, such approaches usually have issues including high equipment costs, requirements for heating and etching, as well as structural and material limitations. In addition, quasi-3D structures by these methods can have problems satisfying the requirements in more complicated and integrated systems. Furthermore, to increase reliability and robustness, there is a need to fabricate metallic nanocomponents with higher strength, longer life, and better precision. Recently, to alleviate the limitations, metal nanoparticle solution and amorphous metal glass have been used as starting materials for fabricating metallic nanostructures.
Forming technology will be well-suited for mass production of small-size features because of its high production output and material integrity. One of the most important advantages of such techniques is that they can shape and strengthen metal components simultaneously due to strain hardening effects. However, investigations on microforming processes have revealed that forming operations are not easily scaled down, particularly because the forming behaviors of these operations at small scales are significantly different from those at the conventional length scales. A few groups have tried to pattern simple linear arrays on surfaces of metallic foils by using direct cold forming. Though extra-hard molds (diamond, SiC) were utilized, distortion of the patterns and damage of molds were encountered in these experiments, which prevented these approaches from being widely adopted.
Experiments disclosed herein have demonstrated that a laser induced shockwave can successfully stamp metal and function materials with micro-scale and meso-scale features. However, it presents very significant technical challenges to obtain nanoscale metallic features with complex shape and high aspect ratio at nano levels. The difficulty of deforming metal materials at nanoscale is mostly due to the limited formability arising from size effects. These effects occur when the sizes of mold cavities are close or smaller than those of metallic grain. The present system and method are intended to improve upon and resolve some of these known deficiencies.